Heat microwave oven or oven to 200C. grease muffins baking tray or line medium size muffin cups with paper baking cups. Mix all of the ingredients excepted diced pineapple. Beat strongly 1 minute with whisks or electric mixer until just combined. Add pineapple stir a little bit with spatula. Divide batter evenly among muffin cups. Bake about 15-25 minutes or until golden brown. Transfer to wire rack, cooled it down first or it's ready to serve it hot or cold with coffee or tea.